Rily likes to collect records last year she have 15 records in her collection now she has 24 records what is the percent increase of heart of collection

You are trying to find Markup, thus you will need to use these 2 equations.

Markup=New-Original
Markup= 24-15
Markup=9

Markup%=Markup/Original*100
=9/15*100
=0.6*100
=60

Thus, your percent increase/Markup%=60%
There is a 60% increase in her records collection.

The year before the 10s so it was like when caveman were alive